1. Technical Field
The present invention relates to a power generation device and the like for inducing current to a coil according to a principle of electromagnetic induction.
2. Related Art
A wide variety of applications is anticipated of a power generation device capable of generating power with a simple operation involved in daily performance. This is because the power generation device can operate small electric machinery and apparatus that requires instantaneous power for simple operation without a power source such as a battery. Therefore, the power generation device has been widely researched.
For example, US 2011/0285487 A (published Nov. 24, 2011) discloses an electromagnetic energy converter, including two electromagnetic members and an electric coil, for converting machine energy to electric energy. JP 2009-516802 W (published Apr. 23, 2009) discloses a self-power generation device including a magnetic circuit that passes through a central opening of an excitation coil for a plurality of times to form at least one loop.
A structure of a conventional power generation device shown in US 2011/0285487 A and JP 2009-516802 W will be described based on FIGS. 21A and 21B. FIGS. 21A and 21B show an internal structure of the conventional power generation device, where FIG. 21A is a cross-sectional view when the power generation device is in an initial state, and FIG. 21B is a cross-sectional view when the power generation device is in a final state.
As shown in FIG. 21A, a protrusion 18a and a protrusion 18b are respectively arranged in an extending manner on a spool 19a and a spool 19b with a central part C of an armature 11 interposed therebetween. The armature 11 is attracted at attracting positions S1 and S2 by the magnetic force of an end 13a of a yoke 12a and an end 13c of a yoke 12b. The armature 11 is thus supported in an orientation of diagonally passing through a space defined by the spool 19a and the spool 19b. 
As shown in FIG. 21B, when a spring 14 is pushed down at an operation position W, the armature 11 rotates with the central part C as a supporting point. The direction of the magnetic flux of a permanent magnet changes so as to cooperatively operate with the rotation of the armature 11 and hence the magnetic flux passing through a coil 16 fluctuates, so that the power generation device can induce current to the relevant coil.
The conventional power generation device still has a problem in that the operation force that needs to be applied on the operation position W is significantly large as compared to the force exerted by the daily performance. In other words, the conventional power generation device lacks in usability since the user feels a sense of discomfort if a force larger than usual is necessary or the user needs to be conscious of strongly pushing in the spring 14.
A structural defect of the conventional power generation device causes the above problem. In other words, as shown in FIGS. 21A and 21B, the armature 11 always rotates with the central part C as the supporting point, and thus the conventional power generation device requires an operation force greater than the sum of the magnetic forces by the two ends (the end 13a and the end 13c in FIG. 21A, the end 13b and the end 13d in FIG. 21B). The sum of the magnetic forces is not large enough to cause problems in operating the armature 11 but is large enough to an extent of causing the problems described above.
The simplest method for solving the above problems is to advantageously apply the principle of leverage by extending the distance from the central part C to the operation position W. However, such a method is not a preferred method since it enlarges the power generation device and newly causes problems of stretching the operation stroke, and the like.
If a large operation force (or long operation stroke) is required for power generation under the condition of a constant power generation amount, this precisely means that the power generation efficiency is not satisfactory. The unsatisfactory power generation efficiency due to the structural defect may not be ignorable, not only in the application of causing the small electric machinery and apparatus to perform a simple operation, but also in other applications (e.g., application that requires continuous power generation of a certain extent, and the like).